A Sphinn thread has discussion around the topic of how much Digg might not like SEO sites or blogs.
Back when Digg was first getting started, SEOs flocked to it, as a way of driving traffic and ultimately links, to help promote the site in the search engines. In fact, this site was often features on Digg's home page, not because I gamed it or wanted the links, in fact, it often put stress on my server, which I didn't want. It was featured because, on occasion, we write something that is quality. The last time we were featured on the Digg home page was in June 2007 for a brief period until it was manually removed. Since then, hundreds of people submitted our content to Digg and none of it made it "hot."
Personally, I gave up caring. But there is no doubt, the Digg community doesn't like the SEO community. It is understandable and it is their community.
The Sphinn thread discusses some of those reasons.
Forum discussion at Sphinn.